Damping device

ABSTRACT

The invention relates to a damping device, particularly for damping or avoiding pressure surges such as pulses, in hydraulic supply circuits, preferably in the form of a silencer, comprising a damping housing which surrounds a damping chamber (19) and has at least one fluid inlet (11) and at least one fluid outlet (13) and a fluid receiving chamber (19) which extends between said fluid inlet (11) and fluid outlet (13), wherein, during operation of the device, a fluid flow crosses the damping chamber (19) in a through-flow direction (15), coming from the fluid inlet (11) in the direction of the fluid outlet (13), and wherein at least parts of the fluid receiving chamber (19) extend in at least one extension direction transversely with respect to the through-flow direction (15). The invention is characterised in that the fluid receiving chamber (19) immediately adjoins the fluid inlet (11) and the fluid outlet (13) and is delimited by at least one yielding wall part (4).

The invention relates to a damping device, in particular for damping or avoiding pressure surges, such as pulses, in hydraulic supply circuits, preferably in the form of a silencer, comprising a damping housing which surrounds a damping chamber and has at least one fluid inlet and at least one fluid outlet and a fluid receiving chamber which extends between the fluid inlet and the fluid outlet, wherein, during operation of the device, a fluid flow crosses the damping chamber in a through-flow direction, coming from the fluid inlet in the direction of the fluid outlet, and wherein at least parts of the fluid receiving chamber extend in at least one extension direction transversely with respect to the through-flow direction.

Damping devices of this kind are state of the art. Such hydraulic dampers, also referred to as sound dampers or silencers, serve to reduce vibrations produced by pressure pulses, which a corresponding hydraulic system is regularly subject to, in particular as a result of the operation of hydraulic pumps. As described in document DE 102 17 080 C1, the known damping devices of this kind have a damping housing in the form of a circular cylinder, which is spherically rounded at both axial end regions, with the fluid inlet and the fluid outlet being located coaxial to the cylinder axis on one respective end region. As the damping chamber, which the fluid flow crosses from the fluid inlet to the fluid outlet, a damping tube is provided in these damping devices, which extends coaxially between the fluid inlet and the fluid outlet and the tube wall has openings to the fluid chamber surrounding the tube. In accordance with the cylinder diameter, the fluid chamber is radially expanded relative to the axial through-flow direction defined by the damping tube.

Given this prior art, the problem addressed by the invention is to provide a damping device of the kind considered which, with a simple construction, is distinguished by particularly effective damping performance.

According to the invention, this problem is solved by means of a damping device having the features of claim 1 in its entirety.

According to the characterizing part of claim 1, a significant feature of the invention is that the fluid receiving chamber is immediately adjacent to the fluid inlet and the fluid outlet and is delimited by at least one flexible wall part. With a construction which is simplified by the elimination of the damping tube, a single cavity forms a resonator system formed from the damping chamber and the fluid chamber together. Because the fluid receiving chamber is delimited by at least one flexible wall part, the device according to the invention is distinguished not only by a simpler construction, but also by increased efficiency with respect to its fluid volume and its weight, with the damping effect being increased in particular in the lower frequency range. Compared with known silencers of this kind, in which an increase in pulses between the pump and the inlet of the silencer can occur, the invention also significantly reduces this risk too.

A particularly efficient damping effect can be achieved in exemplary embodiments in which the fluid receiving chamber forms a disk-like hollow space inside the damping housing. This disk shape can be cylindrical or in the form of a polygon or any other shape which is not circular.

The flexible wall part can particularly advantageously be formed by means of a membrane spanning the disk-like hollow space, which separates the fluid receiving chamber in the damping housing from an expansion chamber. The latter provides free space which allows the membrane certain flexibility.

The arrangement can particularly advantageously be such that a support for the membrane is provided in the expansion chamber. The strength of the support permits adjustment of the stiffness of the membrane and thus its damping performance.

Alternatively, the thickness of the membrane and/or its material properties can also be selected such that, even without a support, adequate flexibility and elasticity is ensured.

Particularly advantageously, a spring arrangement can be provided as a support of the membrane in the expansion chamber. Instead of or in addition to the spring arrangement, a gas cushion for supporting the membrane can also be provided in the expansion chamber.

In particularly advantageous exemplary embodiments, the arrangement is such that, for support of the membrane, a coupling of the expansion chamber with the fluid side of the damping device is provided. This coupling can be formed by a fluid connection between the fluid receiving chamber and the expansion chamber.

In one particularly advantageous exemplary embodiment of the invention, in which the damping housing is formed from several parts, the following components can be provided:

-   -   a pot-like base part, which has a disk-like center recess with a         delimiting wall forming a disk surface of the disk-like hollow         space and with the fluid inlet and the fluid outlet, and     -   a flange-like cover part which, with an engagement connection         piece, engages in a flush manner in the center recess when the         cover part is fixed to the base part.

In such exemplary embodiments, it is advantageously possible to form in the cover part for a spring arrangement supporting the membrane a mount for a compression spring, the free end of which contacts the membrane spanning the damping chamber and the expansion chamber.

For a pressure-resistant formation of the damping housing, the cover part can have, lying diametrically opposite its vertical axis, several throughholes which, passed through by fixing screws, fix the cover part to the base part.

The fixing screws are preferably arranged, leaving the region of the fluid inlet and fluid outlet free, in a uniform manner along an external circumference on the damping housing, which surrounds the disk-like fluid receiving chamber 25.

For connection with a corresponding hydraulic system it is possible to provide at the fluid inlet and/or at the fluid outlet on the damping housing a receptacle for a sealing ring, which surrounds the fluid inlet and/or fluid outlet. The damping housing can be fixed in the manner of a fixing block on third components by means of several fixing bolts, which surround the region of the fluid inlet and/or fluid outlet.

The invention is explained in detail below with reference to an exemplary embodiment depicted in the drawings, in which:

FIG. 1 shows a very schematically simplified sketch-type schematic diagram of the invention;

FIG. 2 shows a perspective oblique view, scaled down compared with a practical embodiment by a scale of 1:3, of an exemplary embodiment of the damping device according to the invention;

FIG. 3 shows a longitudinal section of the exemplary embodiment which is slightly scaled down compared with a practical embodiment;

FIG. 4 shows a top view, on the scale of FIG. 3 and partially cut open, of the base part of the damping housing of the exemplary embodiment;

FIG. 5 shows a sectional depiction corresponding to the cutting line V-V of FIG. 4;

FIG. 6 shows a partial view of only the fluid outlet-comprising connection region of the damping housing of the exemplary embodiment;

FIG. 7 shows a partial view, corresponding to FIG. 6, of the fluid inlet-comprising connection region;

FIG. 8 shows a longitudinal section, depicted on a larger scale compared with FIGS. 3 to 5, of only the cover part of the damping housing; and

FIG. 9 shows, depicted on a smaller scale compared thereto, a perspective oblique view of the cover part, viewed on the inner side forming an engagement connection piece.

FIG. 1 depicts, in a very schematically simplified depiction, a damping housing identified as a whole with the reference numeral 1, which contains a fluid receiving chamber 19, which can be flowed through from a fluid inlet identified with the reference numeral 11, which is immediately adjacent to the fluid receiving chamber 19, to a fluid outlet 13, with the through-flow direction being indicated with flow arrows 2. A delimiting wall of the fluid receiving chamber 19 extending from the fluid inlet 11 to the fluid outlet 13 is formed by a membrane 4, which separates the fluid receiving chamber 19 from an expansion chamber 6. On the side facing the receiving chamber 6, the membrane 4 is supported in the depicted example by a spring arrangement 8. In addition, to generate a pressure cushion formed in the expansion chamber 6 for the membrane a pressure line 10 is provided, by means of which the expansion chamber 6 can be supplied with the inlet-side fluid pressure of the damping device or else with a pressure cushion, for example a gas cushion. To obtain the fluid pressure in the expansion chamber 6, the pressure line 10 is connected as a connection line to the line (not depicted) which supplies the fluid inlet 11. The additional FIGS. 2 to 9 depict in greater detail an exemplary embodiment of the damping device according to the invention.

Of these, FIGS. 2 and 3 show the exemplary embodiment of the damping device in the assembled state. The damping housing 1 depicted closed in these figures consists of two main parts, namely a base part 3, which is depicted separately in FIGS. 4 and 5, and a cover part 5, which is depicted separately in FIGS. 8 and 9. The base part 3 and the cover part 5 each have the same contour, so that they are circumferentially flush with one another in the assembled state (FIG. 2), with the contour corresponding to a circular line, which nevertheless has, on two diametrically opposite sides, a planar flattening 7 and 9. The fluid inlet 11 of the damping housing 1 is located in the part of the flattening 7 belonging to the base part 3 and the fluid outlet 13 is located in the part of the flattening 9 belonging to the base part 3, with the inlet 11 and the outlet 13 being aligned with the axis of the through-flow direction identified in FIG. 4 with the reference numeral 15. On each of the flattenings 7 and 9 there are four threaded holes 16, which are arranged in the corner regions of the rectangular flattenings 7 and 9 and which permit the fixing of the damping housing 1 by means of threaded bolts 17.

Inside the damping housing 1, the fluid receiving chamber extending between the fluid inlet 11 and the fluid outlet 13, which at the same time acts as a damping chamber, is formed by a cavity in the form of a disk-like hollow space 19. It has the form of a circular disk in the form of a flat circular cylinder, the one disk surface of which is delimited by a flat wall 21 which, in the base part 3, which is formed like a pot by means of a central, sunk center recess 41, forms the inner base surface thereof. As can be seen most clearly from FIG. 5, the base part 3 delimits with the inner side wall 22 of the pot the circle diameter of the circular disk-like hollow space 19 related to the central axis 23. The fluid inlet 11 and fluid outlet 13 are each formed by holes in the flattenings 7 and 9, which open into the hollow space 19 flush with the delimiting wall 21 forming the inner pot base.

In the assembled state, as depicted in FIG. 3, where the cover part 5 engages with a circular cylindrical engagement connection piece 39 in the center recess 41 in the base part 3, the membrane 4 forms the wall part, which delimits the hollow space 19 forming the fluid hollow space on the top side, i.e. on the side lying opposite the wall 21. The membrane 4 lies on a circumferential circular ring surface 25, which forms the inner end surface of the cover part 5. This circular ring surface 25 surrounds the expansion chamber 6, which has the form of a recess concentric to the central axis 23 in the cover part 5. An additional recess 14 located inside the expansion chamber 6, which is likewise concentric to the central axis 23 and which has a smaller diameter than the expansion chamber 6 and extends to the vicinity of the top side of the cover part 5, forms a housing for a screwed pressure spring 12 of the spring arrangement supporting the membrane 14.

In the case of a membrane 4 consisting of a metallic material said membrane is preferably fixed by means of a weld joint with its circumferential edge 26 on the circular ring surface 25 of the cover part 5. This can be realized by a full penetration welding realized from the outside of the membrane 4 by means of an electron beam welding process (laser welding). In the case of a membrane 4 consisting of an elastomer, an adhesive joint with the circular ring surface 25 can also be provided. In the assembled state, cf. FIG. 3, the membrane 4 extends as the top delimiting wall of the hollow space 19 flush with the respective adjacent fluid inlet 11 and fluid outlet 13 just like the bottom wall 21 forming a delimitation. In an embodiment which is not depicted in detail, the membrane can also be clamped at the edge for the fixation thereof in the housing.

When the fluid inlet 11 and fluid outlet 13 are each formed by a hole of 12 mm diameter in a practical exemplary embodiment, the disk-shaped hollow space 19 has a depth of 12 mm. In such an exemplary embodiment, the internal diameter of the hollow space 19 can be in the region of 100 mm, with an external diameter of the damping housing 1, outside of the flattenings 7, 9, of 160 mm for example.

As FIGS. 8 and 9 show, the cover part 5 has a flange part 27 with fixing holes 29. The flange part 27 has the same contour as the base part 3, and is thus circular, apart from the flattenings 7 and 9, so that the interruption-free external shape is produced for the assembled overall device, as depicted in FIG. 2. The fixing holes 29 are, as FIG. 9 shows, provided on a partial circular arc outside of the region of the flattenings 7, 9. Corresponding to the fixing holes 29, threaded holes 31 are provided in the base part 3, which are formed as blind holes in the planar top side 33 of the base part 3 and which are provided for fixing screws 35, which penetrate the fixing holes 29, in order to fix the cover part 5 with its flange surface 37 at the top side 33 on the open side of the pot of the base part 3.

In the fixed state, the circular cylindrical engagement connection piece 39 extending coaxially from the flange surface 37 of the cover part 5 engages in the center recess 41 in the base part 3, which is delimited by the inner side wall 22 of the pot of the base part 3. This engagement in the screwed state is depicted in FIG. 3, wherein the membrane 4 forms the top delimiting wall of the hollow space 19. For the sealing of the hollow space 19 relative to the cover part 5, a sealing ring 45 is inserted in an annular groove 43 incorporated in the side wall of the engagement connection piece 39. As FIG. 7 shows, at the flattening 7 assigned to the fluid inlet 11 an annular groove 47 is provided for a sealing element sealing at the connection point. It goes without saying that a corresponding sealing arrangement can be provided in a corresponding manner on the flattening 9 assigned to the fluid outlet.

Due to the symmetrical housing construction, the inlet side and the outlet side can be exchanged possibly with changed sealing geometries. Due to the disk-like damping chamber with a cavity expanding transversely to the actual through-flow direction, a highly efficient silencer is achieved, which has little weight relative to its predefinable fluid volume. In addition, there is only a slight amplification, if any, between the silencer and a hydraulic pump which can be connected thereto. 

1. A damping device, in particular for damping or avoiding pressure surges, such as pulses, in hydraulic supply circuits, preferably in the form of a silencer, comprising a damping housing (1) which surrounds a damping chamber (19) and has at least one fluid inlet (11) and at least one fluid outlet (13) and a fluid receiving chamber (19) which extends between the fluid inlet (11) and the fluid outlet (13), wherein, during operation of the device, a fluid flow crosses the damping chamber (19) in a through-flow direction (2, 15), coming from the fluid inlet (11) in the direction of the fluid outlet ((13), and wherein at least parts of the fluid receiving chamber (19) extend in at least one extension direction transversely with respect to the through-flow direction (2, 15), characterized in that the fluid receiving chamber (19) immediately adjoins the fluid inlet (11) and the fluid outlet (13) and is delimited by at least one flexible wall part (4).
 2. The damping device according to claim 1, characterized in that the fluid receiving chamber forms a disk-like hollow space (19) inside the damping housing (1).
 3. The damping device according to claim 1, characterized in that the flexible wall part is formed by a membrane (4) spanning the disk-like hollow space (19), which membrane separates the fluid receiving chamber in the damping housing (1) from an expansion chamber.
 4. The damping device according to claim 1, characterized in that a support (8; 12) for the membrane (4) is provided in the expansion chamber (6).
 5. The damping device according to claim 1, characterized in that a spring arrangement (8) is provided as the support of the membrane (4) in the expansion chamber (6).
 6. The damping device according to claim 1, characterized in that a pressure cushion for supporting the membrane (4) is provided in the expansion chamber (6).
 7. The damping device according to claim 1, characterized in that, for support of the membrane (4), a coupling (10) of the expansion chamber (6) to the fluid side of the damping device is provided.
 8. The damping device according to claim 1, characterized in that the damping housing (1) is formed from several parts comprising a pot-like base part (3), which has a disk-like center recess (41) with a delimiting wall (21) forming a disk surface of the disk-like hollow space (19) and which has the fluid inlet (11) and fluid outlet (13), and comprising a flange-like cover part (5) which, with an engagement connection piece (39), engages in a flush manner in the center recess (41) when the cover part (5) is fixed to the base part (3).
 9. The damping device according to claim 1, characterized in that, a mount (14) for a compression spring (12) is formed in the cover part (5), the free end of which contacts the membrane (4) spanning the damping chamber (19) and the expansion chamber (6).
 10. The damping device according to claim 1, characterized in that the cover part (5) has, diametrically opposite its vertical axis (23), several throughholes (29) which, passed through by fixing screws (35), fix the cover part (5) to the base part (3).
 11. The damping device according to claim 1, characterized in that the fixing screws (35) are arranged, leaving the region of the fluid inlet (11) and fluid outlet (13) free, in a uniform manner along an external circumference on the damping housing (1), which surrounds the disk-like fluid receiving chamber (19).
 12. The damping device according to claim 1, characterized in that, on the fluid inlet (11) and/or on the fluid outlet (13) in the damping housing (1), a receptacle (47) for a sealing ring is provided, which surrounds the fluid inlet (11) and/or fluid outlet (13).
 13. The damping device according to claim 1, characterized in that the damping housing (1) can be fixed in the manner of a fixing block on third components by means of several fixing bolts (17), which surround the region (7,9) of the fluid inlet (11) and/or fluid outlet (13). 